The use of endoscopes for diagnostic and therapeutic treatment is rapidly expanding. To improve performance, endoscopes have been optimized to best accomplish their purpose. For instance, there are "bleeder-scopes" with one large or two smaller operative channels to ease high-volume suction and/or conveying to the viewing site a therapeutic catheter (i.e. electrocautery, polypectomy snare, laser optic fiber, biliary stent, gallstone basket, etc.)
The size of the therapeutic catheter is inherently predetermined by the size of the operative channel of the endoscope. Some of the therapeutic catheters can change their size as soon as they passed through the scope and come out from the distal end of the scope into the operative field. Polyp-grasper catheter, wall stent biliary stent, gallstone basket are some of the examples. Large size (compared to the size of the regular operative channel which is 3.2 mm) subjects of interest could be held by above mentioned catheters in front of the distal end of the scope but they cannot be removed or introduced through the operative channel of the scope which is frequently the case (i.e. a piece of the polyp, a gallstone, a foreign object, or a stent, etc.) In such cases, usually the subject of interest is held by the "grasping part" of the operative catheter in front of the distal part of the scope after which the whole complex of endoscope, plus catheter plus subject of interest is withdrawn from the body. A great deal of time is lost for example in the case of right colonic polyp/polyps since for every polyp removal the scope is removed and reintroduced to the site of the polypectomy through the entire, sometime very tortuous colon (1.5 meter long), or to check for the absence of bleeding from the site/sites of the polypectomy.
The size of the operative channel of the endoscope has become a dominant and simultaneously limiting factor in the expanding of the boundaries of the therapeutic endoscopy in existing and potentially new techniques. For instance, suturing or stapling through the flexible endoscope is still in its infancy.
For the laparoscopy there is a stapling device described in any textbook for laparoscopic cholecystectomy, but it staples ducts or vessels by being applied to the external surfaces of those structures and device itself is not flexible.
For the flexible endoscopy there were publications of the experimental stapling (by C. P. Swain et al. in Gastrointestinal Endoscopy, 1989, 35(4), p. 338-339) or sewing devices (by C. P. Swain et al. in Gastrointestinal Endoscopy, 1986, 32(1), p.36-38). Those devices have to be mounted on the distal end of the scope before its insertion into the body. Both of those devices inevitably obstruct the front view and the whole introduction of such complexes would have to be performed through an overtube as a protective sheath, preinserted inside the hollow organ. The overtube itself has its own limitations (due to its relative rigidity it could not be passed into the small intestine or deep into the colon).
The other device used with flexible endoscope is the one applied for the ligation of the esophageal varices with resin bands (BARD Company product, procedure described in common textbook). In that case, cylinders with bands also have to be mounted on the distal tip of the scope before introduction into the body. One can apply only one band at a time so that the scope has to be withdrawn every time for remounting a new band at the endoscopic tip. An overtube has to be used for multiple reinsertion of the scope, which could be traumatic.
There are no known stapling/sewing or banding devices that could be delivered to the operative field through the operative channel of the scope.
In the endoscopy field, different types of the "overtubes" or endoscopic sheaths have been described. U.S. Pat. No. 4,646,722 (by F. E. Silverstein, et al.) described a protective disposable endoscopic sheath which is applied over the external surface of the flexible endoscope to prevent contamination of the scope with fecal bacteria and perhaps to avoid costly disinfection. This sheath has to be introduced over the scope like a "stocking" from its distal end up before the procedure starts, that is when the scope is outside the body.
Similar protective disposable sheaths are described in U.S. Pat. No. 4,741,326 (by C. O. R. Sidall, et al.) which also must be installed over the scope from its distal end before the procedure starts.
There is an overtube commonly used in endoscopy to remove a foreign body from the intestine or stomach (particularly, when foreign object has sharp ends, i.e. safety pin). That overtube is described in any endoscopy textbook. Usually it is a tube, only slightly flexible, with the diameter larger than the one of the endoscope, which is pre-inserted over the external surface of the endoscope and held over the proximal end of the endoscope while its distal end is being inserted into the hollow organ and advanced to the depth of interest. Then an overtube is slid over the external surface of the endoscope. Then the endoscope, with the sharp object being held in front of its distal end (since it cannot be retracted inside the small operative channel) is withdrawn inside the overtube. Thus, the overtube protects the pulmonary system and esophagus as a protective sheath.
There are multiple overtubes of different shape, length and flexibility (there is even one with small operative channel inside its wall, described by S. Kitano in British Journal of Surgery, 1987, 74, p. 603-606). However, there is a common denominator for all of them that is all of them are cylindrical tubes that have to be inserted over the external surface of the endoscope from its distal end, when the scope is outside the body. So the operator must know in advance that he is going to need one and pre-insert it over the scope before starting the procedure. Thus, the scope would have to be withdrawn and reinserted should the need for overtube occur (increasing the risk of potential complications as well as making the procedure lengthy and somewhat cumbersome).
It is an object of this invention to improve this state of the art by providing improved protective sheath structure.
It is a further object of the invention to create a new family of the catheters for flexible endoscopes that traverse not through the internal operative channel of the scope, but rather over its external surface. As a regular "internal" catheter the external catheter could be used in the middle of ongoing procedure without having to withdraw the scope for assembly, as it is a case with commonly used overtubes.